Telephone switching system.



F. A. LUNDQUIST.

TELEPHONE SWITCHING SYSTEM.

APPLICATION FILED NOV-15,1916.

//7 V8/7 for: Fran/r A Zzmdyw'szf UNITED STATES PATENT o nIoE.

FRANK A. LUNDQUIST, on NEW YORK, 1v. Y., ssIGNoR T0 wns'rnmv ELno'rRIo oom- PANY, INCORPORATED, on NEW YORK, N. Y., A CORPORATION on NEW YORK.

TELEPHONE SWITCHING SYSTEM.

Application filed November 15, 1916. Serial No. 131,457

To all whom it may concern: Be it known that I, FRANK A. LUNn UIsT, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone Switching Systems, of which the following is av full, clear, concise, and exact description. p

This invention relates to telephone switching systems of the class in which connection is made between a call initiating line and a connecting circuit by means of automatically operating mechanism, the operation of which is controlled by the operation of closing the line circuit by removing thc receiver from the switchhook in initiating a call. The object of this invention is to provide means whereby the operating mechanism will not respond to the condition existing upon a called line at the termination of a conversation when the called party. is the last to hang up his receiver, whereby'connecting circuits will not be unnecessarily seized by the operation of said mechanism.

In general this invention consists in the provision of means whereby the operation, responsive to energization of the cut-off relay of a called line before the operation of the line relay of that line, will disable the operating circuit of the switching mechanism associated with that line and will maintain it disabled until both the line and cutofi' relays have been deenergized by the disconnection of the two lines and the opening of the called. subscribers telephone line at the substation.

More specifically, this invention consists of the provision of a circuit breaker in the operating circuit of the switching mechanism, which circuit breaker is' operated in response to the operation of the cut-off re lay to open the circuit through the switching mechanism and is'moved again into circuit closing position by means of an electromagnet, the circuit for the winding of which is completed only upon the deenergization of both the line and cut-off relays.

In the drawings, Figure 1 is a diagram Specification of Letters Patent.

of apparatus and circuits illustrating this lnvention; Figs. 2 and 3 are diagrams illustrating the position assumed in the operation of the parts embodying the features of this invention. p

In Fig. 1, in which a part of an automatic telephone system is 1 illustrated schemati cally, 2 and 3 represent subscribers stations which are adapted to be connected for conversation through the agencyof switch contacts 5, 5, 5, 6, 6, 6 and 7, 7, 7, which-contacts may be controlled by automatic switches, or' 1n any suitable way, The apparatus at each, of the subscribers stations 2 and 3 is of a.

well-known and standard type, and need not be described herein.

a description of theoperation of a system.

Assuming subscribers station 2 to be that of the calling subscriber and station 3 that of the called subscriber, and that the con nection has already been extended to the called line through the operation of the switches 5, 5, 5, 6, 6, 6 and 7, 7, 7 in. a wellknown manner, we'will consider the condi-j tion now existing. In the first place, a cutoff relay 10,-associated with the line of the called station 3, will be energized over a circuit including the lower ones of the contacts 5, 6 and 7. Upon energization of the winding of the cut-off relay 10 an armat ure 11 is attracted. At its lower end this armature is adapted to operate contact anvils 12 and 13, and is provided near its upper end with a finger 14 extending at right angles thereto,

and on its upper end with an insulating but-v Patented Jan. 1918.

r The invention may be bestunderstood by cuit. The switch may be of the type which automatically hunts the calling line, or the type which automatically hunts an idle connecting circuit, both being well-known in the art;

Upon the movement of the armature 11, the finger le thereon engages a contact anvil '25 of the line relay '18, thereby causing said anvil to close a contact'27, which is also included in the circuit of the switching mechanism 23. The closing of contact- 27. would ordinarily; complete the circuit of the switching mechanism 23, but owing to the condition established by the operation of thecut-ott relay 10, this circuit is open at the contact 22., The parts will remain in the position illustrated in Fig. 2 so long as the two lines are connected for conversation.

At the complains of the conversation both subscribers will hangup their receivers in the usual marnier.w The hanging up of the calling subscribers receiver will cause the openingof contacts "5, 5, 5, 6, 6, 6 and 7, 7, 7, and thereby break ,the circuit through the winding of the cut-ofi' relay 10 whereupon a spring 30 draws the armature 11 back to normal position against astop 31 and with, a metallic portion thereof in electrical contact'with the-projection 20 on the arm 21. If'at this time the called subscribers receiver has not been returned to the switchhook the line relay '18 will .be energized due to theclosure ofcontacts 16 and 17 of the cut-oil relay, and the contact 27 ofthe line relay will remain closed and the various parts will remain in the position shown in Fig, 3 with the circuit through the switching mechanism 23 open at the contact 22. If, however, the called subscriber has' opened his line circuit, then the line relay'18 will be deenergized, and the contact anvil25 thereon will. be in engageme'nt with theprojection 14 on the armature 11, and a :cirouit; will be closed from battery 35 through contact anvil 25, armature'll,circuitjbreaking arm 21 and winding of an electromagnet 37 'to ground. The energization of'the winding of electromagnet 37 causes it to attract the arm 21, whereby it is'swungjinto position with the projection 20thereon resting upon the insulating button 15 on the armature 11, thereby closing contact21 ,as"shown in Fig. 1, thereby placing thecircuit ot theswitch 23 in condition to receive current from battery 85 upon energization 'of'the' line relay 18.

f at aimdc snl 7 i 1. Ina telephone switchingsystem, calling andfcalled linesfswitching mechanism associated v with each; ofsai'd; lines and operating automatically upon the closure of a calling 1in Q'CQ neet1sa al' ng aewi h an d e I1 e iI g.J jci 'f qitflin j and, l p t-p5 r ays associated'witli ach'of saidliirsfind means controlled by said line and cut-off relays for preventing the operation of the switching mechanism of a called line when said called line is held closed after disconnection of the calling line.

2. In a telephone switching system, calling and called lines,switching mechanism associated with each ofsaid lines adapted upon the initiation of a'c'all to connect the calling line with an idle connecting circuit, a cut-off relay associated with the called line and adapted to be energized and deenergized upon the connection and disconnection of a calling line with the called line, a line relay associated with said called lineand adapted tobe operatedthrough normally closed contacts of said cut-otf relay when the line associated therewith isclosed, an operating circuit for said switching mechanism controlled by said line relay, and means controlled by said cut-ofl relay over thecalling line to disable said switching mechanism operating circuit until the called linefis opened;

3. In a telephone switching system, sub-i scribers hues, a connecting c1rcu1t common.

to a plurality of subscribers lines, switching mechanism associated with said subscribers line for connecting it with an idle connecting circuit upon the initiation of a call thereover, an operating circuit for said switching mechanism, a line relay for controlling 'said operating circuit, 'a cut-off relay for normally controlling the operation of said line relay, and means controlled by the energization of said cut-oti relay for disabling the operating circuit-of said switching mechanism and by a'subsequent deenergization thereof and ofthe line relayfor rendering said operating circuit responsive to a subsequent energization of said line relay. 7

4. In a telephone switching system, a subscribers line, a connecting circuit, switching mechanism associated with a subscribers line and adapted upon the initiation of a call thereover to connect said subscribers line with aconnecting circuit, an operating circuit for said switching mechanism, a line relay adapted to close said circuit, a cut-off relay, circuit breaking means operated upon the energization of said cut-01f relay for disabling said operating circuit, and means for restoring said circuit hreakingmeans controlled by the deenergization of said line relay.

5. Ina telephone switching system, a: sub; scribers line, a connecting circuit, switching mechanism associated with said subscribers line and adapted upon the initiation, ofa call thereover to connect said subscribers line with a connecting circuit, an operating circuit'for said switching mechanism, aline relay adapted to close sald circuit, a pivotal lever contact controlled thereby for disabling said operating circuit, a cut-off relay, a second lever controlled by the energization of said cut-oil relay for causing the operation of said first mentioned lever to open its contacts, an electromagnet for restoring said first mentioned lever to circuit closing position, and an energizing circuit for said electromagnet closed through the armature,

of said line relay in its normal position and 10 including said levers.

In Witness whereof, I hereunto subscribe my name this 14th day of November, A. D.

FRANK A. LUNDQUIST.

Copies of this potent my be obtained for live cents each, by addressing the "Commissioner 0! Istsnts, Washington, D. 0." 

